WO 2009/092505 describes the production of insulating polyurethane foams, where porous solids, in particular zeolites, are used as nucleating agents.
EP 0057838 A1 describes the production of gel cushions, where the gel is composed of a high-molecular-weight matrix made of covalently crosslinked polyurethane, and, securely bound within the matrix via secondary valence forces, liquid dispersion medium made of one or more polyhydroxy compounds. The gel cushions are produced by casting the reaction mixture into prepared casings, where the gel reaction is completed.
EP 0511570 A1 describes gels based on reaction products of polyols and polyisocyanates, where polyols used comprise mixtures of polyols with different hydroxy numbers. Again, the gels are produced by casting the reaction mixtures into prepared casings, where the gel reaction is concluded.
EP 1125975 A1 describes the production of gels based on reaction products of polyisocyanates and polyols which comprise at least one pyrogenically produced oxide of a metal or metalloid in order to improve mechanical tensile strength and elongation at break. Here again, the shaping of the gel is achieved by casting the reaction mixture into a casing or mold.
In Rheol. Acta (2005) 44, 644-653 (DOI 10.2007/s00397-005-0446-3), Saint Michel et al. describe the changes in the rheological properties of mixtures of a silica-gelled polymer matrix comprising polyol, catalyst and surfactant caused by addition of CaCO3 particles with a particle size in the micrometer range. The surfactant used comprises a polydimethylsiloxane/polyoxyethylene copolymer. According to the first complete paragraph in the right-hand column on page 650 of that document, the surfactant was found to have no effect on rheological properties.
A disadvantage of the gels described and/or of the process for production thereof is restriction to moldings which are obtainable via casting and optionally subsequent trimming.